Cassette assembly and unit dose medication cart using the cassette assembly

ABSTRACT

A medication cart also holding at least one drawer or tray and at least one bin supported on the tray containing an array of drawers and bins, and a multi-level cassette assembly. An internal locking mechanism secures the cassette assembly when it is positioned in the medication cart, and an external locking mechanism secures the cassette assembly outside of the medication cart. In addition, the cassette assembly includes a mechanism that selectably provides access to an entire tray and all bins carried in it at one time or that provides access to single bins carried on the tray one at a time. This mechanism, more particularly, (a) permits a tray to be nearly fully withdrawn from the cassette assembly thereby exposing a major portion of all carried bins to access all of their contents, and (b) permits the tray to be only partially withdrawn from the cassette assembly so that only a minor portion is exposed but such that each bin can independently be removed from the tray one at a time to access its contents.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S.Provisional Patent Application No. 60/650,529, filed Feb. 8, 2005, whichis hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a mobile cart for storing andtransporting items, and more particularly to a medication cart featuringa cassette assembly ideally suited for storing and dispensingmedication.

2. Description of the Prior Art

Mobile medication carts for storing medical and related patient supplieshave been used for many years. Medication carts are typically used inhospitals or other health care facilities, and are wheeled from room toroom transporting, for example, medication to be dispensed to patients.

Two well-known medication carts are manufactured by Drustar® andArtromick Int'l.®. Both medication carts use a cart frame supported oncasters and are designed to receive an array of drawers, multi-levelcassettes, shelves, etc. Each level of the cassette contains a pluralityof pull-out bins, with the bins on different levels sometimes varying insize (i.e., width). Both medication carts also provide locking systemsfor securing the medication and other items in the cart.

In addition, Artromick Int'l.® offers a patented drawer slide module,which is the subject of U.S. Pat. No. 5,211,461, for use with theirmedication cart.

InterMetro Industries Corporation, a company related to the assignee ofthe subject application, also manufactures and sells medication carts.In one type of mobile cart, known as the METROFLEX® cart, twointerlocking side/bottom panels are joined together to form the lateralsides and bottom of the cart and a back panel is secured to theside/bottom panels. A top portion is added to complete a 3-sidedenclosed cart. The interior sides of the cart are corrugated to supportan array of differently sized drawers and bins, and shelves or otheraccessories can be provided on the outer sides of the cart. TheMETROFLEX® cart is the subject of U.S. Pat. No. 5,016,948, No.5,673,983, and No. D 323,915.

In U.S. Pat. No. 5,673,983, also assigned to the assignee of the presentinventors, a cassette assembly is described that includes a cassettetray designed to be partially withdrawn. In this regard, Prior Art FIG.14 shows a cassette tray with a block 158 on the underside of ahorizontal ledge 146. The block interfaces with a notch in a frame ofthe cassette assembly to indicate a normal stop position. At this stopposition, the cassette tray is partially withdrawn, and individual bins22 in the tray become accessible by lifting a bin over a vertical lip ofthe tray and sliding it out. U.S. Pat. No. 5,673,983 (the “'983 Patent”)is incorporated herein in its entirely by reference.

However, further improvements in medication carts are desired. Forexample, it is desirable to provide a medication cart such as thatdisclosed in the '983 Patent, having increased versatility. Inparticular, it is desirable to provide a cassette assembly for use withsuch a cart that permits selection between accessing a full cassettetray and all of the bins carried by it at one time or individual bins ona cassette tray one at a time.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to provide an improvedcassette assembly for use in a medication cart.

More particularly, it is a principal object of the present invention toprovide a cassette assembly for a medication cart of the type disclosedin the '983 Patent, that can selectably provide access to an entire trayand all bins carried in it at one time or that can provide access tosingle bins carried in the tray one at a time. This object is achievedby providing a mechanism that selectably (a) permits a tray to be nearlyfully withdrawn from the cassette assembly thereby exposing a majorportion of all of the carried bins to access all of their contents or(b) permits the tray to be only partially withdrawn from the cassetteassembly so that only a minor portion of each bin is exposed but suchthat each bin can independently be removed from the tray one at a timeto access its contents.

Thus, in accordance with one aspect of the invention, a cassetteassembly comprises a frame for supporting at least one cassette tray, atleast one tray slidably supported in the frame, and at least one binreceived in the cassette tray. Locking means can secure the cassettetray in the frame. A cassette tray limiting device limits slidingmovement of the cassette tray out of the cassette assembly so that onlya minor portion of the bin is exposed. However, the bin and tray areconfigured so that any one bin can nevertheless be removed from the trayindependently of other bins. An actuator actuates the cassette traylimiting device.

In accordance with another aspect of the invention, a cassette assemblycomprises frame means for supporting at least one cassette tray, theframe means including side panels with corrugated interior surfaces andribbed outer surfaces. At least one cassette tray is slidably supportedin the frame means on the corrugated interior surfaces. At least one binis received in the cassette tray, and locking means can secure thecassette tray in the frame. In addition, the cassette assembly includesmeans for limiting the sliding movement of the cassette tray, andactuating means for actuating the means for limiting the slidingmovement of the cassette tray.

In accordance with yet another aspect of the invention, a cart comprisesan enclosed structure including a plurality of support posts, at leasttwo side walls supported between the support posts, each side wallhaving a corrugated interior surface, a bottom platform supporting thesupport post and the side walls and a top platform fitting over thesupport posts and the side walls. In addition, a cassette assembly isremovably supported in the enclosed structure. The cassette assemblyincludes a frame for supporting at least one cassette tray, the frameincluding side panels with a corrugated interior and ribbed outersurfaces, with the ribbed outer surfaces engaging with the corrugatedinterior surface of the side walls. At least one cassette tray issupported in the frame; at least one bin is received in the cassettetray; and locking means secures the cassette tray in the frame. Inaddition, a cassette tray limiting device limits the sliding movement ofthe cassette tray, and an actuator actuates the cassette tray limitingdevice.

These and other objects, aspects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof the preferred embodiment taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medication cart in accordance with the'983 Patent that can incorporate an improved cassette assembly utilizingthe present invention;

FIG. 2 is a perspective view of a support post forming a part of thatcart;

FIG. 3 is a top plan view of the support post shown in FIG. 2;

FIG. 4 is a fragmented partial view of FIG. 3, isolating a slot in thesupport post;

FIG. 5 is a perspective view of a frame assembly forming a part of thecart shown in FIG. 1;

FIG. 6 is a perspective view of a modified interior side panel for usein the frame assembly shown in FIG. 5;

FIG. 7A is a fragmented top plan view of a support post in use in a backcorner of an enclosed structure for the cart of FIG. 1;

FIG. 7B is a three-axis coordinate system and a schematic view of a sidepanel used in the cart of FIG. 1;

FIG. 8 is a fragmented top plan view of a support post in use in a frontcorner of the enclosed structure;

FIG. 9 is a perspective view of a multi-level cassette assemblygenerally in accordance with the present invention;

FIG. 10 is a perspective view of a top or bottom component of thecassette assembly;

FIG. 11 is a perspective view of a right side panel of the cassetteassembly;

FIG. 12 is a perspective view of a left side panel of the cassetteassembly;

FIG. 13 is a perspective view of a cassette tray used in the cassetteassembly;

FIG. 14 is a partial perspective view of the underside of the right sideof the cassette tray shown in FIG. 13, configured in accordance with theprior art as described in the '983 Patent and in accordance with thepresent invention;

FIG. 15 is a perspective view of a cassette bin that may be carried in acassette tray;

FIG. 16(A) is a partial perspective view of the right side panel andpart of an external locking mechanism for the cassette assembly;

FIG. 16(B) is a partial front elevational view of a locking bar shown inFIG. 16(A);

FIG. 16(C) is a cross-section of the locking bar shown in FIG. 16(B);

FIG. 17 is an exploded perspective view of an improved multi-levelcassette assembly in accordance with the present invention, whichprovides the advantages noted above;

FIG. 18 is a perspective view of a left side panel of the cassetteassembly depicted in FIG. 17;

FIG. 19 is a partial perspective view of the underside of the left sideof the cassette tray shown in FIG. 13 and in accordance with the presentinvention; and

FIG. 20 is a partial perspective view of the right side of the undersideof the tray shown in FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a medication cart 10 in accordance with the presentinvention that is constructed generally as described in U.S. Pat. No.5,673,983 (the “'983 Patent”). While this structure is known from thatpatent, it is useful to describe it here as background. FIG. 1 to 16 areessentially taken from the '983 Patent to provide such background.

Generally, the cart includes a frame assembly 12 supported on casters14. A plurality of drawers 16 of various sizes (i.e., depths) areslidably supported in the frame assembly, and hinged side pods 18 aresupported on the sides of the cart to swing out toward the front asdisclosed in the '983 Patent.

The medication cart features a cassette assembly 20 that includes aplurality of pull-out cassette trays provided on different levels, eachof the trays being configured to carry a plurality of individual bins.In accordance with the subject invention, the medication cart includes asecurity system for preventing unauthorized access to the drawers andthe cassette trays and bins, and the cassette assembly includes its ownsecurity system for securing the trays and bins even when the cassetteassembly is not in the cart. Further, as will be described in detailbelow, the cassette assembly incorporates a mechanism that selectablypermits all of the bins in one tray to be fully accessed at one time oreach of the trays to be accessed individually one at a time while theremaining trays stay substantially concealed in the cassette assembly.(It is to be understood that the cassette assembly of the presentinvention is described as a part of a larger medication cart. However,the principles of this invention may be used with equal advantage in astand-alone cassette assembly.)

Initially the basic cart structure will be described.

Details of the frame assembly 12 are shown in FIGS. 2 through 8. Theframe assembly is based on a platform system using a plurality offlanged support posts and side panels.

A support post 30 in accordance with the subject invention isillustrated in FIGS. 2, 3 and 4. The support post 30 is generallycomprised of an interior post 32 and a plurality of radially extending,equally spaced flanges 34. The post is designed to be verticallydisposed in normal use and can be supported at its lower end by a baseplatform, a foot, a caster, etc. In a single-wide platform, which ispreferred for the medication cart, four support posts are used togetherto provide corner supports for the frame assembly.

The interior post 32 is preferably tubular in shape, with a circularcross-section and interior 36 and exterior 38 concentric wall surfacesas best seen in FIGS. 2 and 3. The flanges 34 preferably extend alongthe entire longitudinal length of the interior post. In addition, theflanges and interior post are preferably formed by conventionalextrusion techniques to form an integral structure made of, for example,aluminum. However, other comparable means, e.g., pultrusion, roll-formedsteel, could be used to form the support post in accordance with thesubject invention.

The flanges 34, or dovetails, are preferably spaced equi-distant fromeach other around the periphery of the interior post 32 to create asymmetrical support post. Thus, four flanges would be spaced at 90°intervals around the post. Although using four flanges is preferredbecause of the versatility such an arrangement provides, the number offlanges is arbitrary and can vary without departing from the scope ofthe invention. With reference to FIG. 3, each flange has a first portion40, which extends radially from the interior post 32. At the terminalend of each first portion is a transversely-disposed second portion 42.The second portions are formed with arcuate outer surfaces 44, thattogether outline a circumference that is concentric with the interior 36and exterior 38 wall surfaces of the interior post 32. Referring to FIG.2, the outer surfaces 44 of each flange are formed with a series ofequally spaced circumferential grooves 46. The vertically-spaced groovesare desirably provided along the entire longitudinal length of theflanges. In one embodiment, the outside diameter of the support post, asdefined by the arcuate outer surfaces 44, is 1.625″ and the insidediameter is 0.875″.

A slot 48 is formed between each pair of adjacent flanges 34. Because ofthe arcuate shapes of the exterior wall surface 38 and the flanges, theslots can be described as substantially concave T-shaped, with respectto a longitudinal axis of the support post. With reference to FIG. 4,each slot is shaped to have concave-shaped opposite end surfaces 50 and52. The exterior wall 38 forms a convex interior surface of the slot.The contour of the end surfaces and outer wall form a slot that issimple in design but provides maximum flexibility and support. Inaddition, the curved single-wall design of the flanges makes extrusioneasier, is readily cleanable and allows the support posts to beaesthetically integrated into the finished structure as will bediscussed in detail below.

The frame assembly 12 in FIG. 5 is built on a single-wide platformconstructed of four support posts 30. In this embodiment, the supportposts support two exterior side panels 54 and a back panel 56 (unseen inFIG. 6). In addition, interior side panels 58 are disposed side-by-sideadjacent to the exterior side panels 54. Top and bottom platforms 60 and62, respectively, complete the frame assembly. The top platform houses amechanical locking mechanism 64 and an electronic controller 66, bothused for operating a security system that will be described in detailbelow. The completed structure forms a 3-sided enclosed frame assembly,with the front side, or fourth side, open to receive an array ofdrawers, shelves, cassettes, etc., as discussed in detail below.

Each interior side panel includes a corrugated interior surface 68 withan array of corrugations 70 adapted to receive and support drawers,shelves, cassette assemblies or other accessories. The horizontalcorrugations are uniformly spaced in the vertical direction. Small,semicircular openings 72 can be seen in the lateral front face of theinterior side panel immediately below the end of each corrugation. Theopenings extend to the underside of each corrugation but cannot be seenin this view. The openings allow locking fingers, which will bepositioned in each corrugations, to move in and out of the corrugationsas part of the security system that will be discussed below. Openingscan also be provided along the right-hand side of the interior panel 58for the same purpose.

The top and bottom platforms 60 and 62 are preferably formed of a metalframe fitted with a plastic cover. As shown in FIG. 5, the top platformhas a substantially rectangular shape for fitting over the four supportposts 30. The bottom platform 62 is preferably designed, at least in asingle-wide platform, to have a “C”-shape formed to have two extendinglegs 74 defining an open front portion 76. By cutting out the frontportion of the bottom platform, the overall appearance of the cart isenhanced, especially when drawers or other accessories are not disposedin the lower part of the cart.

Both top and bottom platforms can be secured to the support posts byusing threaded plugs (unshown) that are force-fitted, for example, inopposite ends of each support post and threaded fastening means fedthrough the top and bottom platforms and into the plugs. In assemblingthe enclosed frame assembly, each support post is positioned on the baseplatform fitted with its cover, and a threaded bolt or other fastener isinserted through a hole in the platform from the underside and intoengagement with the threaded plug. The side panels are then top loadedinto the support posts. Threaded fasteners are inserted through themetal frame of the top platform and into the plugs at the top ends ofthe support posts. Finally, the top cover is fitted over the topplatform. Of course, other comparable means for securing the platformsto the support posts could be used.

In the single-wide platform design as discussed above, the enclosedframe assembly preferably has one support post 30 positioned at each offour corners. In this design, the support posts are spaced, for example,19.841 from center to center. Of course, the spacing of the posts isarbitrary and can be varied to construct different size and shapedstructures. A “double-wide” design platform includes, in addition tofour corner posts, a rear center post and, in an enclosed frameassembly, a front center post.

A slightly modified interior side panel 58′ is shown in FIG. 6. Themodified side panel 58′ differs from the side panel 58 only in that eachcorrugation 70 is formed in two halves to define a dividing slot 74 thatruns the vertical length of the side panel. The modified panel can beused in a two-sided enclosed structure, i.e., a dual access cart,whereby the front and back are open to receive, for example, a cassetteassembly or drawers. In a dual access cart, a thin, flat panel (unshown)can be secured in the dividing slot 74 for dividing the interior of theframe assembly in half.

A recessed opening, or pocket, 76 in the lower part of the interiorsurface 68 and pockets 78 in the back of the interior side panel 58′(and 58) are provided to house various components of a security system.Offset lateral ends, or edges, 80 of the interior panel are received inslots 48 in the support posts as discussed below to secure the sidepanel.

All of the side panels can be made of a polymer material, e.g.,polyethylene, and are preferably blow molded or formed by othercomparable means to form a hollow, two-faced structure. The interiorside panels 58 are also compression molded in part as discussed below.

FIGS. 7A and 8 are top views of the support posts 30 engaging sidepanels in accordance with the present invention. As discussed above, theside panels are top-loaded into the slots 48 of the support posts andrest on the bottom platform, or base, 62.

FIG. 7A is a partial top view of the support post 30 in use as a rightrear support (with reference from the front side of the cart). Clockwisein this figure, the support post 30 secures an interior side panel 58, aback side panel 56, a blank extrusion 80 and an exterior side panel 54.The blank extrusion 80 is essentially a linear trim piece of moldedplastic, preferably extending the length of the support post, that isinserted into an empty slot 48 for aesthetic purposes, i.e., to providea finished look to the enclosed structure.

As FIG. 7A shows, each side panel is shaped to have a neck portion 82and a head portion 84 forming each lateral end for engagement in thesupport post. The head portion is shaped to compliment the shape of theslots 48. In addition, each neck portion is offset from its respectivepanel. Using the exterior side panel 54 in FIG. 7A as an example, andusing the coordinate system in FIG. 7B as a reference, the side panelhas a longitudinal axis A running in the heightwise direction (in theZ-axis direction), a lateral axis B in the widthwise direction (Y-axis)and an orthogonal axis C representing its depth (X-axis). Axis C isorthogonal to both axes A and B. Likewise, the head portion 84 has itsown longitudinal axis E, lateral axis F and orthogonal offset axis G. Inaccordance with the subject invention, the offset axis G of the headportion is transverse to the lateral axis B of the panel. In thismanner, a contour fit is achieved between the panels and the supportposts. As will also be appreciated, lateral axes M of the flanges 34extend in directions either parallel with or perpendicular to thelateral axes (axis B) of the panels they secure. This arrangement allowsthe support posts to be visually integrated into the structure andprovide a clean, aesthetically-pleasing appearance.

FIG. 8 illustrates a support post 30 in use as a right front support inan enclosed structure. In FIG. 8, the slots 48 in the support post 30receive an exterior side panel 54, an interior side panel 58 and a blankextrusion 80 in the same manner as described above in FIG. 7A. In theremaining slot is secured a drawer-abutting extrusion 86 for abutting,e.g., a drawer 16 that is slidably received in the enclosed frameassembly. As discussed in detail below, the drawer is provided with asurface, e.g., one or more ribs, that is slidably supported on thecorrugated surface 68 of the interior side panel 58. As shown in FIG. 8,the drawer-abutting extrusion 86, which is preferably a resilientplastic, includes an abutting face 88 for contacting the fully closeddrawer and a locking face 90 for contacting a part of the drawer andpreventing it from being accidentally pulled out.

A multi-level cassette assembly 20 in accordance with the invention ofthe '983 Patent is shown generally in FIG. 9. This cassette assembly isprovided with improved features as will be described in greater detailbelow. It includes a frame 102 formed by a top component 104, whichincludes a handle 106, a plurality of side panels 108, a bottomcomponent 110 and a back panel (unshown). The bottom component hasessentially the same configuration as the top component but does notinclude a handle. An isolated view of the top (or bottom) component 104is provided by FIG. 10.

The multi-level cassette assembly supports a cassette tray 112 on eachlevel, and each cassette tray contains a plurality of pull-out cassettebins 22. A lock 114, which is part of an external locking mechanism, issecured in a front face of the top assembly. While the cassette assemblyin this figure provides three levels, the number of levels (whichcorresponds to the number of cassette trays) can of course vary withoutdeparting from the scope of the invention. The components comprising thecassette assembly are preferably made of a polymer plastic, e.g., ABS,and can be formed by conventional molding techniques.

The side panels 108 are shown in detail in FIGS. 11 and 12, with FIG. 11illustrating a right side panel for use on the right-hand side of thecassette assembly and FIG. 12 showing a left side panel for use on theleft-hand side of the cassette assembly. A single right and left sidepanel are used for each level of the cassette assembly. Each side panelis preferably an integrally formed piece of molded plastic.

With reference first to FIG. 11, the side panel includes a lateral face116 formed with two elongated ribs 118. The ribs are shaped tocomplement the corrugated surface of the interior side panels 58 asdiscussed above so that the cassette assembly can be slid into the frameassembly to be supported thereby. At the front of each rib 118 is anopen slot 119 for receiving a component of the security system whichwill be discussed below. The top and bottom edges of the side panel areprovided with a plurality of male/female connectors 120/122 forsnap-fitting the side panel to other side panels or top or bottomcomponents when assembling the cassette assembly. The male connectors120 are best seen in FIG. 12.

At the rear end of the side panel is formed a U-shaped panel interface124 for receiving the flat back panel of the cassette assembly. A frontedge 126 of the side panel is formed to have both an elongated slot 128and a through-hole 130 running through it. The slot receives part of theexternal locking mechanism that will be described below. A hollow rod(unshown) made of, for example, aluminum is inserted through the holeand stabilizes the assembled cassette frame.

FIG. 12 best illustrates the corrugated interior surface of the sidepanel. Corrugations 132 form a slot 134 therebetween for receiving thecassette tray 112. Elongated recesses 136 formed in the corrugationsinterface with the cassette tray in a manner described below.

To assemble the frame, the side panels are snap-fitted together usingthe male and female connectors to provide as many levels as desired. Theformed left and right sides can then be snap-fitted to the bottomcomponent and a back panel can be fit into the panel interfaces in theside panels and into a portion of the bottom component. Hollow rods canthen be loaded into the elongated holes 130 in both right and left sidepanels, and the external locking mechanism is positioned in theelongated slot in the right side panels. The top component can now beplaced on the side walls. Screws or other fasteners are then insertedthrough holes 131 in the top and bottom components and into threadedends of the hollow rods to complete the assembly.

The cassette tray 112 that is received in each level of the cassetteassembly is shown in FIGS. 13 and 14. With reference to FIG. 13, as seenfrom the top and right, the cassette tray is formed to have a flatbottom surface 138 surrounded on three sides by a vertical edge 140. Atthe front of the tray is a front face 142 which provides a small lip 144at the front edge of the bottom surface 138. The edges on the left andright sides of the tray extend into horizontal ledges 146 for resting onthe corrugations 132 in the side panels 108 of the cassette assemblyframe. A channel 148 with a notched portion 150 is formed at the frontpart of the ledges. The notched portion is part of an internal lockingassembly and will be engaged by a locking finger to secure the tray inthe cassette assembly frame.

FIG. 14 shows a portion of the underside of the cassette tray as seenfrom the bottom and right, and illustrates a flexible latch 152 thatforms part of the external locking assembly. The latch is cantileveredfrom the front face and includes, at its free end, an abutting face 154and a sloping, or angled, face 156. The sloping face allows the latch toflex upwardly when receiving a horizontal force. A small block 158located beneath the notched portion 150 will interface with the recess136 in the corrugation 132 and indicate a normal stop position of thecassette tray as it is withdrawn from the frame.

The cassette tray 112 supports a plurality of bins 22 as shown in FIG.9. The size (i.e., width) of the bins can be varied to best fit theend-user's needs. For example, FIG. 9 shows a cassette assembly with 6bins supported on the top level, 4 bins supported on the middle leveland 3 bins supported on the lower level. An individual bin 22 isillustrated in FIG. 15.

As can be seen there, each bin has a front end 160 that includes a frontwall 163 and a hollow downwardly open finger pull 166 formed on thefront wall 163. The bin can be supported on a cassette tray 112 againshown in FIG. 13 with its bottom 165 resting on the bottom surface 138of the tray and the front wall 163 below the finger pull 166 looselyabutting the lip 144 on the tray. The bin has a length that issubstantially equal to the distance between the lip 144 and the opposingback vertical edge 140 of the tray 112. Accordingly, engagement of thefront wall 163 of the bin with the lip 144 of the tray prevents the binfrom being withdrawn from the tray in a direction parallel to the traybottom surface 138. Moreover, the bins and trays are dimensioned so thatwhen a tray is fully inserted in the cassette assembly in a retractedposition, a bin is obstructed by an upper adjacent tray or in the caseof the top most tray by top of the cassette from being withdrawn fromthe supporting tray.

However, when a tray is withdrawn from the cassette assembly to awithdrawn position, a bin may be pivoted upwardly about its rear bottomedge on the bottom tray surface 138 to permit the bin front wall 163 toclear the tray lip 144 so that it can be removed from the tray.

FIGS. 16(A)-16(C) show additional components of the external lockingassembly. This locking assembly is designed to lock the cassette trays112 when the cassette assembly is removed from, i.e., external, to themedical cart, hence the name “external locking mechanism.” An internallocking mechanism in the frame assembly secures the cassette trays whenthe cassette assembly is inserted in the medication cart.

With reference to FIG. 16(A), a bolt lock 168, which is mounted in thetop assembly 104 as shown in FIG. 9, actuates a saw-tooth locking bar170 to operate the external locking assembly. The bolt lock, which isconventional per se, includes a locking barrel 172 and an extendedT-bolt 174 that moves in and out of the barrel when a key is insertedinto the lock barrel and turned 180°. Bolt locks manufactured by theHURD LOCK Co. (H75N and H75C series), in Greeneville, Tenn., have beensuccessfully used in the external locking assembly. Comparableassemblies besides the bolt lock could be used to actuate the lockingbar without departing from the scope of the invention. A pin 176 extendsfrom the T-bolt and engages an angled slot 178 in the flag-shaped topportion 180 of the locking bar 170. A vertical slot 182 in the topportion interfaces with the top assembly 104 to vertically guide thelocking bar.

A partial front view of the locking bar 17 is shown in FIG. 16(B). Thelocking bar is preferably formed from metal, e.g., steel, and is shapedto include an elongated bar 171 and at least one locking tooth 184. Arelief 173 is shown at the lower end for metal forming purposes (i.e.,to prevent the metal from cracking as it is bent). Another relief forthe same purpose is provided toward the upper end of the elongated bar171. The elongated bar 170 is formed, e.g., bent, to have an L-shapedcross-section as evident in FIG. 16(C). A first leg 173 of the bar fitsin elongated slot 128 in the side panels. Only one locking bar isnormally provided in each cassette assembly and usually disposed in theright side panels. A plurality of the teeth 184 is evenly spaced alongthe length of the locking bar. One tooth is preferably provided for eachside panel and moves, with actuation of the locking bar, in and out of alocking position. In the locking position the tooth 184 is substantiallyeven with the lower corrugation 132 (i.e., the bottom of the slot 134).

FIG. 16(A) shows the locking bar in the up, or locked, position, wherebythe tooth 184 will engage the latch 152 on the underside of the cassettetray. In this position, engagement between the tooth and the abuttingface 154 of the latch will prevent the cassette tray from beingwithdrawn from its retracted position in the cassette assembly to itswithdrawn position.

If the cassette tray is already withdrawn when the external lockingassembly is actuated, the shape and flexibility of the latch permit thetray to be inserted into the cassette assembly frame and subsequentlylocked. When inserting the tray, the flexible latch will flex upwardlywhen the sloping face 156 slides over the tooth, thus allowing thedrawer to be inserted and locked.

To unlock the cassette assembly, the bolt is actuated to move the T-boltand thus the pin 176 in the direction of arrow x. This sliding movementforces the locking bar downward through a camming action between the pinand the angled slot 178. In the down position, the cassette tray is freeto slide in and out of the cassette assembly frame with the tooth 184located low enough to permit the latch 152 and its abutting face 154 topass over it.

The external locking assembly has been disclosed in terms of locking thecassette trays. As will be appreciated, however, locking the cassettetrays effectively locks the bins and prevents access to the contentstherein. By virtue of the vertical lip 144 on the cassette tray 112 andthe close fit between the structure immediately above the bins, i.e.,either the front face of another cassette tray or the top assembly, theindividual bins cannot be withdrawn unless the cassette tray is slid outa sufficient amount, e.g., one inch, such that the bin can be liftedover the vertical lip and then slidably withdrawn. Thus, by preventingthe cassette tray from being withdrawn, the bins can be securely locked.

Details of a drawer assembly for use in the medication cart are providedin the '983 Patent.

An improved multi-level cassette assembly 350 in accordance with thepresent invention is shown in an exploded view in FIG. 17. As with themulti-level cassette assembly 20 shown generally in FIG. 9, a frame 102of the improved cassette assembly is formed by a top component 104,which includes a handle 106, a plurality of corrugated side panels 108,a bottom component 110 and a back panel 352.

The multi-level cassette assembly 350 supports a cassette tray 112 oneach level, and each cassette tray may contain a plurality of bins 22. Alock 114, which is part of an external locking mechanism, is secured ina front face of the top assembly in the same manner as discussed above.While the cassette assembly in this figure provides three levels, thenumber of levels (which correspond to the number of cassette trays) canof course vary without departing from the scope of the invention. Thecomponents comprising the cassette assembly are preferably made of apolymer plastic, e.g., ABS and can be formed by conventional moldingtechniques.

The multi-level cassette assembly 350 depicted in FIG. 17 features aselection mechanism 351 for controlling the sliding action of eachcassette tray to permit it to selectably assume one of two positionswhen unlocked. These are a position with each cassette tray nearly fullywithdrawn to a withdrawn position, from the retracted position, in theassembly to expose a major portion of the interiors of all bins at thesame time, and a partially withdrawn or intermediate position with onlya minor portion of each bin exposed, which nevertheless permits each binto be removed from the tray one at a time. The exploded view of themulti-level cassette assembly 350 shows the components of this selectionmechanism, which can be substantially the same mechanical arrangement asthe lock and locking bar on the right-hand side of the cassetteassembly. When the selection mechanism is in a first position, eachcassette tray can be partially withdrawn to the intermediate position.In this position, each individual bin can be accessed by lifting it overthe front lip of the tray and withdrawing the bin completely.

When the selection mechanism is in the withdrawn position, the cassettetray can be nearly fully withdrawn, and direct access to all of the binsin the tray is provided.

The selection mechanism will be described below. First, however, thebasic structure of the cassette assembly will be described. Themulti-level cassette assembly depicted in FIG. 17 also has levers 368and 370 mounted in the front face of the top of the assembly. Levers 368and 370 each connected to a latch 372 and are each biased by springs(unshown) to urge the latches 372 outwardly. Each latch 372 engages witha slot (unshown) in side panel 58 of the frame assembly. When a latch372 is engaged with the slot in opposing side panels, the cassetteassembly is secured in the medication cart 10. Sliding the leverstogether against the bias of the springs loads the springs and retractseach latch 372 toward the interior of the cassette assembly. The latches372 are then disengaged from the slots in the side panel 58, allowingthe cassette assembly to be removed by being slid out from themedication cart 10. Similarly, when cassette assembly is to be placed inthe medication cart, urging levers 368 and 370 together allows thecassette assembly to slide into place in the medication cart. Releasingthe levers allows the latches 372 to engage the slots in side panels 58,securing the cassette assembly in place.

The side panels 108 of the cassette assembly are shown in detail inFIGS. 11 and 18, with FIG. 11 illustrating a right side panel for use onthe right-hand side of the cassette assembly and FIG. 18 showing a leftside panel for use on the left-hand side of the cassette assembly. Asingle right and left side panel are used for each level of the cassetteassembly. Each side panel is preferably an integrally formed piece ofmolded plastic.

With reference to FIG. 11, the side panel includes a lateral face 116formed with two elongated ribs 118. The ribs are shaped to complementthe corrugated surface of the interior side panels 58 as discussedabove. At the front of each rib 118 is an open slot 119 for receiving acomponent of the security system discussed above. The top and bottomedges of the side panel are provided with a plurality of male/femaleconnectors 120/122 for snap-fitting the side panel to the other sidepanels or to top or bottom components when assembling the cassetteassembly. The male connectors 120 are best seen in FIG. 55.

At the rear end of the side panel is formed a U-shaped panel interface124 for receiving the flat back panel of the cassette assembly. A frontedge 126 of the side panel is formed to have both an elongated slot 128and a through-hole 130 running through it. The slot receives part of theexternal locking mechanism that was described above. A hollow rod(unshown) made of, for example, aluminum is inserted through the holeand stabilizes the assembled cassette frame.

FIG. 18 best illustrates the left side panel of the multi-level cassetteassembly 350. Parts corresponding to parts of the left side paneldepicted in FIG. 12 are indicated with the same label numbers and adiscussion of them is not provided herein. A front edge 126 of the sidepanel is formed to have both an elongated slot 374 and a through-hole130 running through it. The slot receives the selection rod of theselection mechanism that was described above.

The selection mechanism comprises a saw-tooth selection bar 366 that hassubstantially the same features and characteristics as the saw-toothlocking bar 170 described above and depicted in FIGS. 16(B) and 16(C).The selection bar is actuated by rotation of a toggle 354 shown in FIG.17, the body of which is secured to the cassette assembly by a nut 356.A bolt 358 is attached to the toggle 354 by a screw 360. A pin 362 onthe bolt 358 engages slot 364 of the selection bar. As the toggle 354 isrotated 90°, the pin rotates correspondingly, causing the selection bar366 to move up or down in a vertical direction. As will be appreciated,the toggle 354 can be replaced by a key-operated lock like the lock 114,because the internal components are the same.

FIG. 19 depicts an underside of the cassette tray and illustrates asmall block or stop 376, which depends upon the ledge 146 and forms partof the selection mechanism. When the selection mechanism is in theposition which provides single bin access, namely when the selection baris moved to its first upper position by the toggle, a saw-tooth of theselection bar will interfere with the block 376 allowing the cassettetray 112 only to be partially withdrawn but preventing the tray frombeing fully withdrawn. In other words, the position of the block 376defines a short stop position of the cassette tray when the selectionmechanism is in the up or single bin access position. The small block376 is positioned such that it does not enter the slot 134, and thus,will not interface with recess 136 in the corrugation 132.

In the first or single bin access position, the selection mechanismpermits the tray only to be partially withdrawn from the cassetteassembly so that only a minor portion of each bin is exposed. However,dimensions of the lip 144 of the tray and the front wall 163 of the bin,and the inter-tray spacing are determined so that each tray canindependently be pivoted or tilted, as described with reference to FIGS.13 and 15, clearing the wall 163 from the lip 144 and permitting the binto be withdrawn to expose it completely. Therefore, in this selectedintermediate or single bin access position each tray is accessibleindividually while the remaining trays remain largely inaccessible andin place on the tray.

When the selection mechanism is in the second position, the selectionbar does not engage the block 376, and the tray can be fully withdrawnto the withdrawn position thereby exposing the interiors of all binssimultaneously. A lip 380 of the tray (shown in FIG. 17) will interferewith a small block (unshown) on the underside of corrugation 132 of theside panel and indicate a normal stop position of the cassette tray asit is withdrawn from the frame.

FIG. 20 depicts an underside of the cassette tray. As can be seen inthis figure, the cassette tray in this embodiment does not include ablock corresponding to block 158 on its right-hand side to regulatemovement.

Thus, what has been described is a medication cart that includes animproved cassette assembly. The cassette assembly includes its ownexternal locking assembly for securing its contents when disposedoutside of the medication cart. The cassette assembly is also providedwith a selection mechanism for selectably permitting positioning of atray carried therein in either a single bin access position or in an alltray access position.

Although specific embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Various modifications of andequivalent structures corresponding to the disclosed aspects of thepreferred embodiment in addition to those described above may be made bythose skilled in the art without departing from the spirit of thepresent invention which is defined in the following claims, the scope ofwhich is to be accorded the broadest interpretation so as to encompasssuch modifications and equivalent structures.

1. A cassette assembly comprising: a frame; at least one cassette tray;means for slidably supporting said cassette tray in said frame formovement between a retracted position and a withdrawn position; at leastone bin received in said cassette tray; and a cassette tray limitingdevice for selectably limiting sliding movement of said cassette trayfrom the retracted position to an intermediate position between theretracted and withdrawn positions, wherein when said cassette tray ismoved to the intermediate position at most a minor portion of said binis exposed.
 2. The cassette assembly according to claim 1, wherein saidtray comprises an upstanding lip at its forward end and said bincomprises a front wall adapted to abut said lip when said bin isreceived in said tray.
 3. The cassette assembly according to claim 2,wherein said lip of said tray and said bin are configured to permit saidbin to be pivoted on said tray with said front wall clearing said lipwhen said tray is moved to the limited intermediate position.
 4. Thecassette assembly according to claim 1, further comprising an actuatorfor actuating said cassette tray limiting device.
 5. The cassetteassembly according to claim 4, wherein said actuator is operative toplace said cassette tray limiting device (a) in condition to limitsliding movement of the cassette tray to the intermediate position, and(b) in condition to permit movement of said cassette tray to thewithdrawn position.
 6. The cassette assembly according to claim 1,wherein said cassette tray limiting device includes a rod slidablymounted in said frame for movement between a first position and a secondposition.
 7. The cassette assembly according to claim 6, wherein saidcassette tray includes a stop configured to engage said rod when saidrod is in the first position and when said cassette tray is moved fromthe retracted position toward the withdrawn position.
 8. A cassetteassembly according to claim 7, wherein said rod includes a tooth andsaid stop includes an abutting face for abutting said tooth when saidrod is in the first position.
 9. A cassette assembly comprising: framemeans; at least one cassette tray; means for slidably supporting saidcassette tray in said frame for movement between a retracted positionand a withdrawn position; at least one bin received in said cassettetray; locking means for releasably securing said cassette tray in saidframe in the retracted position; means for limiting sliding movement ofsaid cassette tray, when said locking means is released, from theretracted position to an intermediate position between the retractedposition and the withdrawn position, wherein when said cassette tray ismoved to the intermediate position at most a minor portion of said binis exposed; and actuating means for selectably actuating said limitingmeans (a) for limiting sliding movement of said cassette tray to theintermediate position and (b) for permitting sliding movement of saidcassette tray to the withdrawn position.
 10. A cart comprising: asupport structure comprised of a plurality of support posts; and atleast two side walls supported between said support posts, each saidside wall having a corrugated interior surface; and a cassette assemblyremovably supported in said support structure, said cassette assemblycomprising: a frame including side panels having ribbed outer surfaces,said ribbed outer surfaces being formed to engage said corrugatedinterior surfaces of said side walls of said support structure; at leastone cassette tray; means for slidably supporting said cassette tray insaid frame for movement between a retracted position and a withdrawnposition; at least one bin received in said cassette tray; locking meansfor releasably securing said cassette tray in said frame in theretracted position; means for limiting sliding movement of said cassettetray, when said locking means is released, from the retracted positionto an intermediate position between the retracted position and thewithdrawn position, wherein when said cassette tray is moved to theintermediate position at most a minor portion of said bin is exposed;and actuating means for selectably actuating said limiting means (a) forlimiting sliding movement of said cassette tray to the intermediateposition and (b) for permitting sliding movement of said cassette trayto the withdrawn position.